Immunodetection of Polyphenol oxidase in glandular trichomes ofS. berthaultii,S. tuberosum and their hybrids

Type A glandular trichomes confer insect resistance to the wild potato,S. berthaultii Hawkes by oxidatively polymerizing their contents upon breakage, resulting in insect entrapment. Polyphenol oxidase (PPO) is responsible for the oxidative polymerization of Type A glandular trichome exudate.S. tuberosum L. trichomes possess low amounts of PPO and lack the ability to either polymerize their contents or entrap insects. Polyclonal antibodies raised against purifiedS. berthaultii glandular trichome PPO were used to develop an enzyme-linked immunosorbent assay (ELISA) to quantify PPO content ofS. berthaultii, S tuberosum, and hybrid type A glandular trichomes. The PPO ELISA and immunoblots were used to quantify PPO expression as a function of leaf development and genetic background. PPO accumulates to its maximal levels in trichomes prior to completion of leaflet expansion. In advanced breeding generations, trichome PPO is expressed at levels varying from that found inS. tuberosum to that found inS. berthaultii. By serving as an initial screen for trichome PPO, this ELISA may be useful to assist rapid introgression of this insect resistance trait into adaptedS. tuberosum backgrounds.     

Inheritance of glandular trichomes in crosses withSolanum berthaultii

The inheritance of trichome density and droplet size was investigated in diploid and tetraploid crosses. In haploidTuberosum ×Solanum berthaultii and (S.phureja ×haploid Tuberosum) × S.berthaultii crosses, droplet size on type B trichomes was small or droplets were lacking on F₁ hybrids. Parental phenotypes were recovered in the F₂ and backcross generations. Trichome density was more variable within a clone that was droplet size. Density of both type A and type B trichomes appears to be under the control of small numbers of genes, as parental phenotypes were recovered in the F₂ and backcross generations. The variation observed for each of the three traits studied could not be explained by hypotheses based on the segregation of one or two loci. The insect resistance ofSolanum berthaultii appears to be due to the interaction of several chemical and physical factors, thus potato breeders should handle it as a quantitatively inherited trait.     

玉米抗粗缩病主效QTL (qMrdd1)的基因多效性分析

前期研究中将主效抗病QTL(qMrdd1)定位在第8染色体分子标记M103.4-M105.3之间,该抗病QTL表现为隐性基因遗传,可降低24.2%~39.3%的发病率。通过分子标记检测,在抗病系NT411(供体亲本)和感病系NT409(轮回亲本)回交多代的群体中,选择7个含有抗性QTL(qMrdd1)的杂合单株自交得到分离群体B1、B2、B3、B4、B5、B6、B7和来源于同一回交后代的两对抗感病近等基因系(B8-R、B8-S和B9-R、B9-S),利用这两对近等基因系与自交系A7110、Q319、CT03、昌7-2、43684、43683、43946组配13对杂交种,在植株整个生育期内无粗缩病病毒接种的条件下,在北京、海南和山东种植不同的材料并对7个分离群体和13对杂交种进行农艺性状调查,结果表明,7个分离群体中各基因型植株以及13对杂交种在株高、穗长、穗行数等农艺性状上差异不显著,qMrdd1基因对玉米产量性状不存在多效性现象,可以应用于抗粗缩病育种。     

大豆霜霉病(Peronospora manschurica)抗病性遗传分析

本研究于田间以种植感病品种病粒为感染行,并以田间采集的菌孢子进行接种的方法,对1984年配制的4个杂交组合和1988年配制的4个杂交组合与5个回交组合的F_1、F_2、F_3和B_1代抗感病性进行研究。调查分析表明:大豆霜霉病是由单基因控制的简单遗传,F_1代抗病性为完全显性,F_2代抗病单株与感病单株按3:1分离F_3代出现抗病系和抗病分离系,两类系的比例为1:2。F_1代与感病亲本回交,回交一代抗病与感病单株分离比例为1:1。F_1代与抗病亲本回交,回交一代表现抗病。     

高产稳产抗病水稻新组合T优5537的选育与应用

针对龙特甫A具有配合力好、杂交率高、制种产量高，但育性不稳定的特性，选用具有互补性状的地谷B、珍汕97B与龙特甫B进行复合杂交 ，后代根据育种目标选株与珍汕97A我并经多代回交选育出不育性稳定且基本保留龙特甫A优良特性的新不育系T55A。用其与抗稻瘟病性强的恢复系蜀恢537配制成的杂交稻新组合T优5537具有高效、稳产、稻瘟病性强等特性，于2002年2月通过福建省农作物品种审定委员会审定，具有较好的推广应用前景。     

转Bt基因水稻克螟稻杂交转育后代农艺性状的研究

 对转Bt基因水稻与常规品种的杂交后代进行了GUS活性的组织化学分析和农艺性状考察。结果表明，报告基因gus与抗虫基因 cry1Ab是连锁遗传和协同表达的，利用GUS组织化学染色法可快速筛选抗虫杂种植株；无论是籼粳交，还是粳粳交后代，抗虫和感虫的两类植株间在株高、穗长、单株分蘖数、播始历期和千粒重等主要农艺性状上无显著差异，这无疑为利用Bt水稻培育优良的抗虫品种提供了科学依据。     

Development of elite breeding lines conferring Bph18 gene-derived resistance to brown planthopper (BPH) by marker-assisted selection and genome-wide background analysis in japonica rice (Oryza sativa L.)

Brown planthopper (BPH) is a serious threat to rice production. In this study, we have used the novel resistance gene Bph18 derived from Oryza australiensis and incorporated it into an elite japonica cultivar, Junambyeo, which is highly susceptible to BPH. The Bph18 gene was introduced by marker-assisted backcross (MAB) breeding into Junambyeo. The backcrossed progenies were evaluated for desirable agronomic and grain quality traits and the selection of improved breeding lines while simultaneously evaluating BPH resistance by bioassays in the greenhouse and foreground selection. Of the 26 advanced backcross breeding lines (ABL), four lines showed agronomic traits similar to those of the recurrent parent, with strong resistance to BPH. Molecular genotyping of the four ABL revealed the conversion of genotypes closely resembling the genotype of Junambyeo. The percentage of donor chromosome segments in ABL decreased from 12.3% in the BC₂ to 9.4%, 8.4% and 5.3% in BC₃, BC₄ and BC₅ generations, respectively. ABL retained small sizes of the donor chromosome segments on chromosomes 1, 2, 10, 11 and 12 but the genomes of ABL2, ABL3 and ABL4 were homosequential to the recurrent parent on chromosomes 3, 4, 5, 6, 7 and 9 without donor chromosome segment introgression. The ABL1 and ABL2 retained only some small segments of the donor genome on chromosomes 9 and 8, respectively. Fine structure analysis of the Bph18 flanking region between RM511 and RM1584 markers on chromosome 12 showed a progressive elimination of donor-derived chromosome segments from BC₂ to BC₅ generations. The percentage of O. australiensis derived chromosome segment substitution in the recurrent parent background decreased from 28% of the donor parent to 6.7%, 3.9%, 3.4% and 3.4% in BC₂, BC₃, BC₄ and BC₅ generations, respectively. However, it was revealed that the O. australiensis-derived chromosome segment (1320 kb) in ABL containing the Bph18 gene was consistently maintained irrespective of advances in backcross generations. BPH resistant elite breeding lines with agronomic and grain quality traits similar to those of the recurrent parent were successfully developed by foreground and background analysis in japonica background without linkage drag.     

Heritability of agronomic traits correlated with reduced stink bug damage in an F2:3 soybean population derived from IAC-100

In Brazil, some of the most important insect pests causing damage to soybean (Glycine max) are stink bugs. Soybean production would increase if varieties with enhanced resistance were developed. The aim of this work was to examine different traits associated with plant development, and yield-related traits, in an F_2:3 soybean population in a stink bug-infested field and to evaluate genetic parameters and correlations among those traits. The parents and progeny from 229 F₂ plants developed by crossing a resistant cultivar (IAC-100) with a susceptible cultivar (CD-215) were evaluated in three replications in a single environment. Seven agronomic traits and eight indicators of insect resistance were measured. Genotypes showed significant differences for all traits except lodging. The grain-filling period exhibited a positive genotypic correlation of 0.66 with hundred-seed weight, whereas a negative genotypic correlation of ?0.53 was found between pod damage index (%) and weight of healthy seeds. In general, a shorter pod-filling period, lower weight of hundred-seeds, lower indices of pod damage, and higher seed-yield per plant were phenotypic traits of genotypes resistant to these insects.     

Mechanisms of resistance to potato leafhopper,Empoasca fabae (Harris), in potato

Potato genotypes were evaluated for resistance to natural infestations of the potato leafhopper,Empoasca fabae (Harris), in the field. Characterization of Type A and B glandular trichomes, phenolic properties of Type A trichomes, glycoalkaloid content and composition,E. fabae adult and nymph infestation, leaf damage (hopperburn), yield, and yield reduction were determined on genotypes PI 473331 and PI 473334 (accessions ofSolatium berthaultii (Hawkes)), NY123 and Q174-2 (advanced hybrids), and Elba and Allegany (commercial cultivars). Regarding the Type A trichome, PI 473334 was most pubescent, followed by PI 473331, both had high levels of enzymatic browning; on PI 473334 no glycoalkaloids were detected, while on PI 473331 solamargine and solasonine were present. Those genotypes were the least infested by adults; moreover, nymphs were never found on their leaves. PI 473331 and Q174-2 possess Type B trichomes, the latter had levels of Type A trichome comparable to the first and to NY123, while displaying high levels of phenolic oxidation of Type A and very low levels of glycoalkaloids. Although Q174-2 had intermediate infestation ofE. fabae, it suffered a yield reduction comparable to the control cultivar Allegany. The density of Type A trichomes of NY123 was relatively low, even though the browning assay results were significantly elevated. Foliage of this genotype was found to contain the four types of glycoalkaloids studied at high levels.Empoasca fabae infestation on NY123 was intermediate, and it yielded well on infested plots, but suffered an intermediate yield reduction. Elba presented densities of Type A similar to NY123. It suffered the lowest yield reduction despite its high levels of leafhopper infestation and hopperburn. Its tolerance might be associated with its phenology, since it is a late-maturing cultivar. High scores of the modified enzymatic browning assay were correlated with high infestation and high leaf damage. Results indicated a significant correlation between leafhopper infestation and hopperburn.     

芸薹属油菜种质资源抗(耐)菌核病、病毒病的鉴定

芸薹属油菜种质资源抗(耐)菌核病、病毒病的鉴定结果表明:1.抗菌核病的基因主要存在于B和C染色体组,抗芜菁花叶病毒(TuMV)的基因主要存在于C染色体组。2,农艺性状与抗菌核病性存在相关;B.campestris有效分枝点高度、B.carinata的株高、有效分枝点高度与抗性指标RRA分别呈显著和极显著正相关,B.juncea二次有效分枝数与RRA呈显著负相关,B.napus的上述性状与RRA相关不显著。3.油菜单株产籽量和产油量随病情加重而下降,达显著或极显著程度。     

The inheritance of resistance to soft rot (Erwinia carotovora subsp.atroseptica) in diploid potato families

Soft rot of potato tubers, caused byErwinia (Pectobacterium), is a serious disease affecting potato crops during storage. Studies on the inheritance of resistance to tuber soft rot were undertaken on diploid potato hybrids. A total of 480 clones, derived from 12 families, were examined for resistance to soft rot in laboratory tests over 3 years and for basic agronomic traits in field experiments over 2 years. General (GCA) and specific (SCA) combining abilities were significant in the inheritance of resistance to soft rot; however, GCA for female parents were significant in 1 or 2 years during 3 years of evaluation and SCA was significant for eight, two, and six families out of 10 tested in 1994, 1995, and 1996, respectively. There were also significant differences between years. Moreover, marked interactions for GCA_females × year and SCA × year in the variation of soft rot resistance were found. Broad-sense and narrowsense heritability of resistance, measured as diameter of rotten tissue, was estimated as 0.92 and 0.89, respectively. The maternal effect, evaluated in two sets of reciprocal crosses, was not significant for the genetic determination of resistance to soft rot. No significant relationships were found between resistance to soft rot and the main agronomic traits in the tested diploid families. These results suggest that diploid potato clones with resistance to soft rot can be selected after being evaluated over a few seasons. It is also possible to select clones combining good resistance to soft rot with high yield, superior tuber characteristics, and acceptable starch content. These resistant diploids can be used as male parents in 4x-2x crosses in breeding tetraploid potato resistant to soft rot.     

Induction of systemic resistance and defense-related enzymes after elicitation of resistance by rhizobacteria and silicon application against Ralstonia solanacearum in tomato (Solanum lycopersicum)

Bacterial wilt caused by Ralstonia solanacearum is a devastating plant disease affecting several economically important crops. To trigger plant-mediated systemic resistance against the pathogen, silicon and the rhizobacteria strain Bacillus pumilis were applied as elicitors. The impact of each elicitor in the induction of systemic resistance was evaluated by individual or dual application in pathogen inoculated tomato genotypes. Application of silicon and B. pumilis significantly reduced bacterial wilt incidence by 50.7 and 26.7%, respectively, in the King Kong 2 genotype (moderately resistant) and by 31.1 and 22.2%, respectively, in the L390 genotype (susceptible) but the dual application of the elicitors did not. The pathogen responsive lipoxygenase (LOX) activity was decreased in the silicon-treated tomato plants and no significant difference was detected in B. pumilis treated-pathogen inoculated plants compared to the control. In addition, a non-significant increases of peroxidase (PO) activity and phenylalanine ammonia lyase (PAL) activity were observed in either silicon/B. pumilis treated and pathogen inoculated plants. However, the PO, PAL and LOX activities declined during the dual application due to antagonistic effect of the two pathways triggered by the two elicitors. Therefore, separate application of each elicitor is recommended as the best strategy for induction of systemic resistance against bacterial wilt in tomato with silicon being a stronger inducer than B. pumilis.     

Resistance toErwinia carotovora subsp.atroseptica in second backcross populations of somatic hybrids betweenSolanum tuberosum andS. brevidens

Summary Eleven clones obtained from a cross between cv. Katahdin and fusion products betweenSolanum tuberosum and the non tuber-bearing speciesS. brevidens, were backcrossed again withS. tuberosum (clone AR80-127-5). Small tubers harvested from 583 seedlings of these second backcross (BC2) populations were screened for tuber tissue resistance toErwinia carotovora subsp.atroseptica under aerobic conditions. After multiplication in the field. BC2 clones again were screened for soft rot resistance under aerobic as well as anaerobic conditions. In general, the resistance of the BC2 populations was reduced in comparison with the BC1. Variation for resistance was found within the BC2 populations, but there was no correlation between the results of the three tests performed. Four BC2 populations were also screenned for resistance to blackleg in the field. Significant differences were found between populations for mean percentage of diseased plants, but these differences could not be explained by the resistance of the parental clones.     

Resistance to soft rot (Erwinia carotovora subsp.atroseptica) in tetraploid potato families obtained from 4x-2x crosses

Diploid potato clones, interspecific hybrids ofSolanum species, having in their originS. tuberosum,S. chacoense, S. yungasense, S. phureja, S. gourlayi, andS. demissum, with resistance to soft rot, were crossed to tetraploid potato clones in 4x-2x crosses. The 24 tetraploid families obtained in a North Carolina II design were examined for tuber resistance to soft rot in a laboratory test and for basic agronomic traits in field trials conducted for two consecutive years. In addition, one family originating from a 4x-2x cross of two susceptible parents was tested. Statistical analysis of the data revealed significant general (GCA) and specific combining ability (SCA) effects, year, GCA (female) × year, GCA (male) × year, and SCA × year upon the inheritance of resistance to soft rot. About 35% of the progeny was selected as resistant to tuber soft rot, and of these 11% showed high resistance combined with good tuber yield, tuber weight, and tuber appearance. The relationships between resistance to soft rot and chosen agronomic traits were not noted or were weakly significant and sporadic. The resistance to tuber soft rot found in diploid potato hybrids can be transferred to the cultivated tetraploid pool through 4x-2x crosses, and a high frequency of offspring posses resistance.     

Beneficial effects of Neotyphodium tembladerae and Neotyphodium pampeanum on a wild forage grass

Asexual, vertically transmitted fungal endophytes of the genus Neotyphodium are considered to enhance growth, stress resistance and competitiveness of agronomic grasses, but have been suggested to have neutral or deleterious effects on wild grasses. We studied whether the associations between Bromus auleticus and their endophytes, Neotyphodium pampeanum and Neotyphodium tembladerae, are beneficial for this wild forage grass native to South America. In a greenhouse experiment, 3‐month‐old endophyte‐infected plants (E+) showed enhanced growth relative to their endophyte‐free counterparts (E?). In a one‐year‐long experiment in the field, E+ plants showed higher survival and regrowth rate, and produced more biomass and seeds than E? plants. Only with respect to the seed output did N. tembladerae seem to be detrimental, whereas N. pampeanum did not affect this parameter. No differences were observed with respect to the germination of seeds produced by E+ or E? plants. Loline alkaloids were detected in N. pampeanum‐infected plants. Our results show that, similar to results with agronomic grasses, in wild grasses, the symbiosis with Neotyphodium species could be mutualistic.     

Activity of benzothiadiazole on chrysanthemum yellows phytoplasma (‘Candidatus Phytoplasma asteris’) infection in daisy plants

A commercial preparation of the plant resistance elicitor benzothiadiazole (BTH) (Bion, Syngenta Crop Protection) was tested for its capacity to induce systemic resistance against chrysanthemum yellow phytoplasma (CYP) infection in the Chrysanthemum carinatum plant. Following one 2.4 mM BTH application, plants were exposed to CYP-infective Macrosteles quadripunctulatus leafhoppers. Symptom development and phytoplasma multiplication in the test plants were measured over time. BTH application delayed symptom development and phytoplasma multiplication in treated plants compared with the control ones. CYP titre and symptom severity were significantly lower for the first two weeks post-inoculation in treated plants compared with the control ones, suggesting that systemic acquired resistance (SAR) induced by BTH in C. carinatum is temporary. Higher concentrations of BTH resulted in phytotoxic effects involving the whitening of apical leaves. BTH application was ineffective in reducing the transmission efficiency of CYP by its leafhopper vector. Actually, in both single and group transmission tests, the proportion of infected plants was similar among BTH-treated and untreated plants. The survival of M. quadripunctulatus was unaffected by feeding on BTH-treated daisy plants. Moreover, when leafhoppers were allowed to choose between treated and untreated plants, they showed no preference. We conclude that SAR induced in daisy plants by BTH has no detrimental effects on the vector leafhopper. If the activity of BTH against phytoplasmas is confirmed also on other phytoplasma/host–plant associations, BTH applications might be included in new, more environmentally friendly, integrated management strategies of phytoplasmoses.     

香蕉早花突变体的分离与初步鉴定

以"巴西"香蕉果皮带毛嵌合突变体为材料,利用组织培养方法逐步分离到果皮带毛突变体,并对该果皮带毛香蕉突变体的形态学、解剖学特征和农艺性状进行研究,结果表明:突变体果实覆盖长短不同的表皮毛;果柄、近果柄的花序梗和花苞基部等部位也都覆盖表皮毛;表皮毛是由单个细胞发育而来.突变体生长周期明显缩短,产量与"巴西"香蕉没有显著差异,果实蓟马感染率明显降低,其它农艺性状与其野生型"巴西"香蕉没有明显差异.     

Can resistance in Bemisia tabaci (Homoptera: Aleyrodidae) be overcome with mixtures of neonicotinoids and insect growth regulators?

Tobacco whitefly, Bemisia tabaci is an important polyphagous insect pest which has developed resistance to various insecticides worldwide. Mixtures of insecticides with different modes of action may delay the onset of resistance. Bioassays were performed to investigate the effects of various mixtures of neonicotinoid and insect growth regulator (IGR) insecticides against a susceptible and a resistant strain. The results of the study showed that potentiation ratio (PR) of all neonicotinoids + buprofezin or pyriproxyfen mixtures at 1:1, 10:1 and 20:1 ratios was greater than 1 suggesting synergistic interactions between insecticides. Maximum potentiation occurred at the 1:1 ratio (PR = 1.69–7.56). The PRs for mixture of acetamiprid, thiamethoxam, thiacloprid or nitenpyram with buprofezin or pyriproxyfen at 1:10 and 1:20 ratios were less than 1 indicating antagonistic interactions. Addition of synergists, S, S, S, tri-butyl phosphorotrithioate (DEF) or piperonyl butoxide (PBO) in the insecticide solutions largely overcame the resistance to all tested neonicotinoids, indicating that the resistance was associated with esterases or mono-oxygenases, respectively. Likewise, addition of both DEF and PBO in mixture with neonicotinoids and IGRs also suggested a similar mechanism of resistance in B. tabaci to the tested insecticide groups. The mechanism of synergism between neonicotinoids and IGRs is unclear. Implications of using mixtures to counteract pesticide resistance are discussed. Mixtures of neonicotinoids with buprofezin or pyriproxyfen at a 1:1 ratio could be used to restore the efficacy of these neonicotinoids against B. tabaci.     

No fitness costs associated with resistance of Busseola fusca (Lepidoptera: Noctuidae) to genetically modified Bt maize

A concern regarding planting of Bt crops is that their widespread cultivation could lead to evolution of insect resistance to Bt toxins. In South Africa, the noctuid maize stem borer (Busseola fusca [Fuller]), is resistant to Bt maize (Zea mays L.; MON810) which produces Cry1Ab protein. The presence of fitness costs in resistant populations could be a valuable component of resistance management since the non-Bt maize refuge may select against resistance. The aim of the study was to determine if there are fitness costs associated with Bt resistance of B. fusca. Life history parameters were compared between individuals of a Bt maize resistant B. fusca population when feeding on Bt or non-Bt maize. Similar comparisons were done using a control population. Field collected larvae as well as their F₁-generation were used in the study. The following parameters were compared: pupal mass, moth longevity, fecundity, fertility, larval mass and survival, and sex ratio. Except for LT50-values, no fitness costs were associated with the resistance trait in the highly resistant B. fusca population. The absence of fitness costs and presence of resistant populations may promote the use of a multi-gene strategy which would be expected to impact negatively on fitness.